Potential for cross-transmission of Dictyocaulus viviparus between cattle and white-tailed deer

Development of an in vitro culture system for infectious Dictyocaulus vivip arus larvae made it possible to study the potential cross-transmission of D . viviparus between white-tailed deer (Odocoileus virginianus) and cattle ( Bos taurus). Between 26 September 1995-29 February 1996, six parasite-free bull calves were individually inoculated with 15 to 50 infective third stag e larvae (L-3)/kg of body weight cultured from adult D. viviparus collected from white-tailed deer. Three bull calves were simultaneously inoculated w ith 45 L-3/kg of body weight recovered from cattle either by the Baermann t echnique or by in vitro culture as above. All three calves inoculated with the homologous cattle strain became patently infected while all six calves inoculated with the heterologous deer strain remained negative for the pres ence of D. viviparus in the feces and in the lungs upon necropsy.